K562 is an erythroleukemic cell line widely used as a model for the study of the control of human globin gene expression. These cells do not support transcription of the beta-globin gene (human adult pattern of expression) but do express transcripts of epsilon- and gamma-globin genes (human embryonic and fetal pattern) at very high levels when exposed to a number of inducing agents. Results from this and other laboratories suggest that the control of this pattern of expression is mediated by the presence and/or absence of trans-acting factors which exert their action on sequences corresponding to the promoters of these genes. Sequence specific DNA binding proteins acting on cis-regulatory control elements have been hypothersized to be key elements in eukaryotic gene transcription, and even though considerable progress has been made in their isolation, DNA binding proteins with affinity for the human globin gene promoters have not yet been identified. We have chosen to study the interaction of these factors with DNA sequences belonging to the epsilon-gene promoter. The methodology used DNA sequences belonging to the epsilon-gene promoter. The methodology used included DNase footprinting and the gel retardation assay. By the former, two protective patterns have been detected surrounding the -500 and - 260 nucleotide regions, and by the latter multiple DNA binding activities have been shown, some of which possess specificity. Experiments leading to the detection of the exact sites to which these elements bind are now under course using a combination of these two methods. Further studies will be undertaken to show the functional significance of these factors. Characterization of such factors is crucial in understanding the mechanisms underlying the transcriptional control of human globin genes.